Low carbon steel strip or low alloy structural steel strip is rolled to blank pipe according to a certain spiral Angle (forming angle) then its seam is welded together. The finished product is spiral welded pipe. This method can produce large diameter steel pipe with narrow strip steel. Spiral welded pipe is mainly used for oil and gas pipelines. Its specifications are indicated by outer diameter*wall thickness. The spiral welded pipe has single side welding and double sides welding. The welded pipe shall ensure that the water pressure test, the tensile strength and the cold bending performance of the weld shall meet the requirements.